[WIP] Audit-mode runner

@tyler-ball @sersut 

Pulling my head out of RSpec 3 land to share audit mode runner progress. Will be subbing this out for the work done in the [previous demo](https://github.com/opscode/client-docs/tree/mcquin/audit-runner-demo/mockups/audit) this afternoon, to make sure some of the new configuration options are working as expected.

Unaccounted for TODO items (will update as per discussion):
- [ ] Incorporate Serverspec matchers and types
I'll add the formatter I wrote to the Chef codebase so we can start playing around with that in our setup.  I'll push it to the audit branch.